Metal terephthalamate-thickened greases containing soaps of fatty acids as bleeding inhibitors



United States PatentO METAL TEREPHTHALAMA'I'E-THICKENED GREASES CONTAINING SOAPS OF FATTY ACIDS AS BLEEDING INHIBITORS Bruce W. Hotten, Orinda, Calif., assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Filed July 17, 1957, Ser. No. 672,375

15 Claims. (Cl. 2523'3.6)

This invention is directed to the use of soaps of certain fatty acids as bleeding inhibitors for grease compositions thickened with a metal salt of a terephthalamic acid.

This application is a continuation-in-part of Hotten U.S. Patent No. 2,820,012, filed December 14, 1954.

Although it is essential that a small amount of oil be liberated from grease structures during the lubrication of wearing surfaces, the amount of oil thus available is expected to be only that amount which is sufficient for the proper lubrication of such wearing surfaces. As grease compositions exude large amounts of oil, the greasethickening agent becomes more concentrated, and the concentrated soap mixture thus formed builds up to such a degree as to clog lubrication parts and interfere with the flow of the lubricant to the wearing surfaces. Thus, the excessive bleeding of oil from grease compositions results in a gradual breakdown in lubrication caused by the cutting off of the supply of lubricant to the surface being lubricated.

Of particular concern as thickening agents for the grease compositions of this invention are the metal salts of the terephthalamic acids which are described in patent application Serial No. 475,299, filed December 14, 1954. In general, greases prepared from metal salts of terephthalamic acid have an exceedingly high dropping point; theyare' extremely water resistant; and they are remarkably work stable. These characteristics of grease compositions permit the greases to be used in the lubrication of wearing surfaces over wide temperature ranges with a negligible loss of grease due to emulsification in water. Although the greases thickened with metal salts of terephthalamic acids have the favorable characteristics noted hereinabove, they do have a slight tendency to bleed under certain conditions at high temperatures.

Thus, it is a primary object of the present invention to inhibit high temperature bleeding of greases thickened with metal salts of terephthalamic acids.

In accordance with the present invention, it has been discovered that the bleeding tendency of grease compositions thickened with metal salts of terephthalamic acids can be inhibited by the addition thereto of small amounts of metal soaps of fatty acids. Thus, the grease compositions of this invention comprise oils of lubricating viscosity thickened to the consistency of a grease by metal salts of terephthalamic acids, and having incorporated therein a metal soap of a fatty acid.

The grease compositions described and claimed herein are effective in lubrication of wearing surfaces over wide variations in temperature; they are resistant to bleeding and to emulsification in water; and they are extremely work stable.

Thus, the tendency of metal terephthalmate-thickened greases to bleed during high temperature operation can be inhibited by the addition thereto of a small amount of a metal soap of a high molecular weight fatty acid.

' 'Ihe grease-thickening agents of this invention, that is,

the metal salts of terephthalamic acids, include the metal terephthalamates of the formula:

wherein R is an organic radical, that is, a straight-chain, branched-chain, or cyclic, saturated or unsaturated hydrocarbon radical, M is a metal, and x is a number having a value equal to the valence of the metal M. As a straight-chain or branched-chain radical, R can contain from 1 to 22 carbon atoms. As a cyclic radical, R can contain from 6 to 28 carbon atoms. Preferably, R is an aliphatic radical.

Examples of R include the following radicals: methyl, ethyl, propyl, n-butyl, tertiarybutyl, pentyl, Z-methylbutyl, hexyl, Z-methylpentyl, 2,3-dimethylbuty1, heptyl, isoheptyl, octyl, Z-ethylhexyl, isooctyl, nonyl, decyl, de'cenyl, dodecyl, tetradecyl, ethylhexyl, hexyldecyl, hexadecyl, hexadecenyl, octadecyl, octadecenyl, methylphenyl, ethylphenyl, propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, tetradecylphenyl, octadecylphenyl, octadecenylphenyl, etc. T

The metals include the metals of Groups I, II, III, and IV of Mendeleffs Periodic Table, particularly lithium, sodium, potassium, silver, magnesium, calcium, zinc, strontium, cadmium, barium, aluminum and lead. Because of the increased melting point and improved texture obtained by the grease compositions thickened therewith, it is preferred to use lithium, sodium, and barium metals.

The grease-thickening agents herein are the metal salts of terephthalamic acids, which are exemplified as follows: sodium N-methyl terephthalamate, sodium N-ethyl terephthalamate, sodium N-butyl terephthalamate, sodium N-amyl terephthalamate, sodium N-hexyl terephthalamate, sodium N-octyl terephthalamate, sodium N-decyl terephthalamate, sodium N-tetradecyl terephthalamate, sodium N-octadecyl terephthalamate, sodium N-eicosyl terephthalamate, sodium N-docosyl terephthalamatqsodium N-phenyl terephthalamate, sodium N-methylphenyl terephthalamate, sodium N-butylphenyl terephthalamate, sodium N-hexylphenyl terephthalamate, sodium N-octylphenyl terephthalamate, sodium N-decylphenyl terephthalamate, sodium N-tetradecylphenyl terephthalamate; barium N-methyl terephthalamate, barium N- ethyl terephthalamate, barium N-butyl terephthalamate, barium N-amyl terephthalamate, barium N-hexyl terephthalamate, barium N-octyl terephthalamate, barium N- decyl terephthalamate, barium N-tetradecyl terephthalamate, barium N-octadecyl terephthalamate, barium N- eicosyl terephthalamate, barium N-docosyl terephthalamate, barium N-phenyl terephthalamate, barium N- methylphenyl terephthalamate, barium N-butylphenyl terephthalamate, barium N-hexylphenyl terephthalamate, barium N-octylphenyl terephthalamate, barium N-decylphenyl terephthalamate, barium N-tetradecylphenyl terephthalamate; lithium N-methyl terephthalamate, lithium N-ethyl terephthalamate, lithium N-butyl terephthalamate, lithium N-amyl terephthalamate, lithium N-hexyl terephthalamate, lithium N-octyl terephthalamate, lithium N-decyl terephthalamate, lithium N-tetradecyl terephthalamate, lithium N-octadecyl terephthalamate, lithium N- eicosyl terephthalamate, lithium N-docosyl terephthalamate, lithium N'-phenyl terephthalamate, lithium N- methylphenyl. terephthalamate, lithium N-butylphenyl Patented Oct. 11, 196

U terephthalamate, lithium N-hexylphenyl terephthalamate, lithium N-octylphenyl terephthalamate, lithium N-decylphenyl terephthalamate, lithium N-tetradecylphenyl terephthalamate, etc.

The particular metal soaps of fatty acids which are incorporated in the terephthalamate-thickened grease compositions herein to inhibit the bleeding thereof include the alkali metal and the alkaline earth metal soaps of fatty acids containing from 12 to 20 carbon atoms, preferably from 16 to 18 carbon atoms. Examples of metal soaps of fatty acids used herein as bleeding inhibitors include sodium stearate, sodium palmitate, sodium oleate, potassium stearate, potassium palmitate, potassium oleate, calcium stearate, calcium palmitate, calcium oleate, etc.

The particular ratio of the metal salt of terephthalamic acid to the sodium soap of the above-mentioned fatty acids will depend upon the type and degree of improvement desired in the final grease composition. Thus, the mol ratio of the metal salt of terephthalamic acid to the fatty acid soap can vary from 1 to 20, preferably from 3 to 10. The metal soaps of fatty acids are used in amounts of 0.5% to 5%, by weight, preferably from 1% to 3%, by weight.

Lubricating oils which are suitable base oils for the composition of this invention include a wide variety of lubricating oils, such as naphthenic base, parafiin base, and mixed base; other hydrocarbon lubricants, e.g., lubricating oils derived from coal products, etc. Thus, hydrocarbon and non-hydrocarbon oils may be used.

The hydrocarbon oils may be natural oils derived from petroleum, or they may be synthetic oils produced by polymerization of olefins or by synthesis from coal, carbon monoxide, etc.

Other lubricating oils include alkylene oxide type polymers, dicarboxylic acid esters, liquid esters of acids of phosphorus, alkylbenzene oils, polymers of silicon, etc. Synthetic oils of the alkylene oxide type polymers may be used, e.g., propylene oxide polymers produced by polymerizing propylene oxide, polyethers prepared from alkylene glycols, e.g., ethylene glycol, etc.

The polymeric products prepared from the various alkylene oxides and alkylene glycols may be polyoxyalkylene diols or polyalkylene glycol derivatives; that is, the terminal hydroxy groups can remain as such, or one or both of the terminal hydroxy groups can be removed during the polymerization reaction by esterification or etherification.

Synthetic oils of the dicarboxylic acid ester type include those which are prepared by esterifying such dicarboxylic acids as adipic acid, azelaic acid, suberic acid, sebacic acid, alkenyl succinic acid, fumaric acid, maleic acid, etc., with alcohols, such as butyl alcohol, hexyl alcohol, 2- ethylhexyl alcohol, dodecyl alcohol, etc.

Synthetic oils of the alkylbenzene type include those which are prepared by alkylating benzene (e.g., dodecyl benzene, tetradecylbenzene, eicosylbenzene, etc.).

The above base oils may be used individually as such or in various combinations, wherever miscible or wherever made so by the use of mutual solvents.

The metal soaps of terephthalamic acids are used in amount sufficient to thicken the lubricating oils to the consistency of greases. For example, amounts from 7% to 50%, by weight, may be employed. It is preferred to use from 8% to 20%, by weight.

The following specific examples will serve to illustrate the practices and advantages of the invention.

EXAMPLE I.PREPARATION OF GREASE THICK- ENED \VITH SODIUM N-OCTADECYL TERE- PI-ITHALAMATE A mixture of 66 pounds of methyl N-octadecyl terephthalamate, 6.0 pounds of sodium hydroxide in 6.0 pounds of water, and 132 pounds of a California solventrefined parafiin base oil having a viscosity of 1700 SSU at 100 F. was heated to 320 F. at a pressure of 73 pounds per square inch for 1 hour. The mixture was then blown with air to remove water, after which an additional 35 pounds of the same base oil was added, and the mixture was heated to 600 F.

For the purpose of preparing a grease containing 10% of this sodium terephthalamate, 4.4 pounds of this mix ture was further diluted with 0.88 pound of the same base oil. The whole mixture was then drawn into shallow pans and cooled, after which it was milled through a colloid mill.

The octadecyl radical was derived from a commercial preparation of amines known as Armeen HT, sold by the Armour Company, Chicago, Illinois, and containing 25% hexadecylamine, 70% octadecylamine, and 5% octadecenylamine. of this mixture consists of N-primary amines.

EXAMPLE II.PREPARATION OF A GREASE THICKENED WITH SODIUM N-OCTADECYL TEREPHTHALAMATE A mixture of 54 pounds of methyl N-octadecyl terephthalamate, 268 pounds of a California solventrefined paraflin base oil having a viscosity of 480 SSU at F., and 114.5 pounds of a California solventrefined paraffin base oil having a viscosity of 185 SSU at 210 F., was blended together by heating to a maximum temperature of 250 F. This mixture was cooled to F., and 4.5 pounds of sodium hydroxide in 5 pounds of water, and 9 pounds of oxidation inhibitor was added thereto. This whole mixture was then passed through a Manton-Gaulin homogenizer at a pressure of 2000 psi. and a temperature of 280 F. The resulting grease was heated to 300 F.; re-milled in the Manton- Gaulin homogenizer; and cooled to room temperature.

EXAMPLE III.--PREPARATION OF A GREASE THICKENED WITH SODIUM N-OCI'ADECYL TEREPHTHALAMATE A mixture of 26 pounds of methyl N-octadecy terephthalamate, 102 pounds of a California solventrefined paraifin base oil having a viscosity of 480 SSU at 100 F., and 119 pounds of a California solvent-refined parafiin base oil having a viscosity of SSU at 210 F., was heated to a maximum temperature of 250 F., after which the mixture was cooled to 130 F. There was then added 1150 grams of sodium hydroxide in 1000 grams of water. The mixture was introduced into a Manton-Gaulin homogenizer at 2000 psi. The resulting grease composition was heated to 300 F., and remilled in the homogenizer and cooled to room temperature.

EXAMPLE IV.--PREPARATION OF A GREASE THICKENED WITH SODIUM TALLOWATE A 1000-pound mixture of 21.07% tallow, 3.01% sodium hydroxide in equal weight water, 45.82% of a California solvent-refined naphthenic base oil having a viscosity of 100 SSU at 100 F., and 28.59% of a California solvent-refined naphthenic base oil having a viscosity of 450 SSU at 100 F., was heated to a temperature of 300 F., with rapid stirring, then pan cooled. The tallow acids contain 14.5% stearic acid, 32.5% palmitic acid, 48.3% oleic acid, 2.0% myristic acid, and 2.7% linoleic acid.

Data are presentedhereinbelow in Table I to show the effectiveness of metal soaps of fatty acids as bleeding inhibitors for greases thickened with metal salts of terephthalamic acids. The test greases were prepared by blending the greases of Examples LIV, hereinabove.

The bleeding tests were run as follows, according to Tentative Standard Method 3454-T, which is a part of Federal Test Method Standard No. 791 of December 15, 1955:

90 grams of grease were distributed in a modified front-wheel hub and spindle assembly. The hub was rotated at 660 rpm. for one hour at a spindle temperature of 260 F. Theleakage' ofoii or grease (or both) was then measured.-

Table 1 Test Grease Composition (percent by wt.)

Grease of Example I 100. Grease oi Example II 45. 0 47. 5 Grease of Example III 45. 0 47. 6 Grease of Example IV'. 10.0 5. 0 Thickening Agent: Sodium'lrephthalahl e. 10. 3 10.3 10.0 Bleedmglnhibitor: Sodium Tallowate 2. 2 1. 1 Mol Ratio Sodium Tallowate to Sodium Tomphthalnmam 0 33 o, 17 Physical Properties:

Worked Penetration (P 305 300 305 ASTM Dropping Point, F 449 443 500+ Leakage (grams) 15 8 26 Table II hereinbelow presents further data on the efiectiveness of metal soaps of fatty acids in inhibiting bleeding of grease compositions thickened by metal salts of terephthalamic acids. The grease was prepared by heating the ingredients to 450 F., pan cooling to room temperature, then milling through a A-inch needle valve at 4000-5000 p.s.i. In all instances the greases contained 90% of base oil, which was a California solvent refined parafiin base oil having a viscosity of 480 SSU at 100 F.

These greases were tested according to the Mil-G-3278A Bleeding Test whereby the grease was placed in a (SO-mesh screen cone at 212 F. for a eriod of 30 hours. The percentage weight loss through the screen was t en noted.

In addition to the agents noted herein, the grease compositions of the present invention may contain rust inhibitors (metal petroleum sulfonates), lubricating agents (aromatic phosphates), color correctors, stringiness agents, extreme pressure agents, etc.

I claim:

1. A grease composition comprising a major proportion of an oil of lubricating viscosity, a metal salt of a terephthalamic acid in amount suflicient to thicken said oil to the consistency of a grease, and a metal soap of an unsubstituted fatty acid in amount suflicicnt substantially to inhibit bleeding of said grease composition wherein said metal, in each instance, is a metal selected from the group consisting of alkali metals and alkaline earth metals.

2. A metal terephthalamate-thickened grease composition having incorporated therein, in an amount suflicient to inhibit bleeding of said grease composition, a metal soap of an unsubstituted fatty acid wherein said metal, in each instance, is selected from the group consisting of alkali metals and alkaline earth metals. 1

3. A grease composition comprising a major proportio of an oil of lubricating viscosity thickened to the consistency of a grease with a metal salt of a terephthalamic acid, and having incorporated therein from 0.5% to 5%, by weight, of a metal soap of an unsubstituted fatty acid wherein said metal, in each instance, is selected from the group consisting of alkali metals and alkaline earth metals.

4. A grease composition comprising a major proportion of an oil of lubricating viscosity, in an amount suflicient tothicke'n said 'oil'to the consistency of a grease, a. metal terephthalamate of the formula i/ -NHR i t V wherein R is an'organic radical selected from the group consisting of a straight-chain, branched-chain, saturated and unsaturated radicals containing from 1 to 22 carbon atoms, M is a metal selected from the group consisting of alkali metals and alkaline earth metals, and x is a number having a value equal to the valence of the metal M, and from 0.5% to 5%, by weight, of a metal soap of an unsubstituted fatty acid containing from 12 to 20 carbon atoms wherein the metal of said metal soap is se lected from the group consisting of alkali metals and alkaline earth metals.

5. The grease composition of claim 4, wherein R is an aliphatic radical, M is an alkali metal, and x is 1, and the metal soap of fatty acid is an alkali metal soap.

6. The grease composition of claim 5, wherein the mol ratio of metal terephthalamate to metal soap has a value from 1 to 20.

7. A grease composition comprising a major proportion of an oil of lubricating viscosity, from 7% to 50%, by weight, of a metal salt of N-aliphatic terephthalamic acid, and from 0.5% to 5%, by weight, of a metal soap of an unsubstituted fatty acid wherein said metal, in each instance, is selected from the group consisting of alkali metals and alkaline earth metals.

8. A grease composition comprising a major proportion of an oil of lubricating viscosity, from 7% to 50%, by weight, of a metal salt of N-aliphatic terephthalamic acid, wherein said aliphatic group contains from 1 to 22 carbon atoms, and from 0.5% to 5%, by weight, of av metal soap of an unsubstituted fatty acid containing from 12 to 20 carbon atoms wherein said metal, in each instance, is selected from the group consisting of alkali metals and alkaline earth metals.

9. A grease composition comprising a major proportion of an oil of lubricating viscosity, from 8% to 20%, by weight, of a metal salt of N-aliphatic terephthalamio acid, wherein said aliphatic group contains from 1 to 20 carbon atoms, from 1% to 3%, by weight, of a metal soap of an unsubstituted fatty acid containing from 12 to 20 carbon atoms wherein said metal, in each instance, is selected from the group consisting of alkali metals and alkaline earth metals.

10. A grease composition comprising a major proportion of an oil of lubricating viscosity, thickened to the consistency of a grease with a metal salt of an N-aliphatic terephthalamic acid, wherein said metal is selected from the group consisting of alkali metals and alkaline earth metals, and having incorporated therein from 0.5 to 5%, by weight, of a metal soap of an unsubstituted fatty acid wherein said metal is selected from the group consisting of alkali and alkaline earth metals.

11. The grease composition of claim 10, wherein the aliphatic group of said N-aliphatic terephthalamic acid contains from 1 to 20 carbon atoms, and said fatty acid contains from 12 to 20 carbon atoms.

12. A grease composition comprising a major proportion of an oil of lubricating viscosity, and thickened to the consistency of a grease with an alkali metal salt of an N-aliphatic terephthalamic acid, wherein said aliphatic group contains from 1 to 20 carbon atoms, and having incorporated therein from 1% to 3%, by weight, of an alkali metal soap of an unsubstituted fatty acid containing from 12 to 20 carbon atoms.

, 1,3. A grease composition comprising a major proportion of an oil of lubricating viscosity, "from 8% to 20%, by weight, of a metal salt of an N-aliphatic terephthalamic acid, and from 0.5% to 5%, by weight, of an alkali metal soap of an unsubstituted fatty acid containing from 12 to 20 carbon atoms, wherein the mol ratio of said metal salt of terephthalamic acid to said soap of fatty acid has a value from lto 20.

14. A grease composition comprising a major proportion of an oil of lubricating viscosity, from 8% to 20%, by weight, of an alkali metal salt of an N-aliphatic terephthalamic acid wherein said aliphatic group contains from 1 to 20 carbontatoms, and from 0.5% to 5%, by weight, of an alakil metal soap of an unsubstituted fatty acid containing from 16 to 18 carbon atoms, wheteinthe mol ratio of said metal salt of tereplithalamic acid to said soap of fatty acid has a value, from 3 to 10.

15. A grease compositioncomprising a major proportion of an oil of lubricating viscosity, from 8% to 20%, by weight, of sodium, N-octadecyl terephthalamate, from 057% to 5%., bytweight, of sodium stearate, wherein the mol ratio of said sodium terephthalamate to said sodium stearate hasa value from .1 to 20.

References Cited in the fileofthis patent UNITED :STATES PATENTS 2,820,012 'Hotten Jan. 14, 1958 

1. A GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF AN OIL OF LUBRICATING VISCOSITY, A METAL SALT OF A TEREPTHALAMIC ACID IN AMOUNT SUFFICIENT TO THICKEN SAID OIL TO THE CONSISTENCY OF A GREASE, AND A METAL SOAP OF AN UNSUBSTITUTED FATTY ACID IN AMOUNT SUFFICIENT SUBSTANTIALLY TO INHIBIT BLEEDING OF SAID GREASE COMPOSITION WHEREIN SAID METAL, IN EACH INSTANCE, IS A METAL SELECTED FROM THE GROUP CONSISTING OF ALKALI METALS AND ALKALINE EARTH METALS. 